1. Field of the Invention
This invention relates to a detecting device, and more particularly to a detecting device provided with functions of detecting the focus and detecting the relative movement between an object and the detecting device.
2. Description of the Prior Art
For example, in instruments such as cameras, much importance is attached to the detection of the focus and the detection of the relative movement between an object and the camera to obtain better photographs. That is, the former is useful to always obtain the best imaging condition of the object image on the film surface, or in other words, to always obtain a sharp photograph, and the latter is useful to always obtain a photograph free of image blur on the film surface. Particularly, as regards the latter, a concrete form of output is possible in which whether the selected film exposure time (shutter speed) is sufficiently short to avoid image blur is determined, whereby in an inconvenient case, namely, in a case where the selected film exposure time is too long to avoid image blur, some warning to that effect is effected or photography (shutter release) is automatically inhibited and further the exposure time is automatically shifted to a short time.
Devices for effecting such focus detection and relative movement detection are known. For example, in U.S. Pat. No. 4,218,119 owned by the same assignee of the present invention ("System For Controlling The Exposure In A Camera", Schickedanz, patented on Aug. 19, 1980; corresponding German DE-OS No. 2738804) or U.S. Pat. No. 4,264,161 ("Motion Detecting Device In Exposure Control System For Optical Instruments", Hosoe et al., patented on Apr. 28, 1981; corresponding German DE-OS No. 2844339), a detecting device utilizing the output of a light detecting means to effect both detection of the focus and detection of relative movement is disclosed as a highly rational form of such device.
In these disclosed devices, there is still room for improvement. For example, by achieving not only a combined use of the light detecting means but also a great combined use of the signal processing circuit, it would be possible to simplify the construction of the electric circuit system and thereby greatly reduce the cost of the device, in spite of the device being provided with different functions.